GANEA 2 is a new trial based on patient treated for a large breast tumor with proven axillary involved nodes. Patients enrolled in this trial will have first an axillary sonography with fine needle punction in case of suspected nodes before NAC. This primary evaluation allow to determine two groups of patients : group 1 : patients with proven involved axillary nodes and group 2, patients without proven axillary involved nodes. Patients of group 1, the study group, will undergo SLNB and complete level I-II axillary lymphadenectomy. Patients of group 2 will undergo SLNB and a complete axillary level I-II lymphadenectomy only in the case of detection failure or involved SLN and a SLNB alone in the others cases. Patients of this last group will be followed 5 years in order to evaluate the risk of axillary relapse without lymphadenectomy.